Exploring the Liquefaction Vulnerability of a Single-Span Integral Abutment Bridge Using Centrifuge Modeling

Global warming is causing sea levels to change and increasing the risk of flooding, leading to unexpected changes in the water table. An elevated water table changes the effective soil stresses that support structures, potentially reducing their resilience during earthquakes. Many integral abutment bridges (IABs) were designed and built considering low water table levels. However, the effects of global warming highlight the need to understand the vulnerability of these bridges to liquefaction damage caused by higher groundwater levels. Centrifuge experiments were conducted on a single-span integral abutment bridge model with different configurations. The specific scenarios of dry and saturated foundation soils were considered, while the backfill soil was always dry. The results show that the structural response in both experiments was broadly similar. However, the loss of soil stiffness of the foundation soil due to liquefaction caused a significant increase in bending moments of the abutment walls. The bridge settled uniformly by about 0.3 m (12″), 10 times higher than the allowable design limit value of 30 mm (1.18″) for integral abutment bridges with importance factor III, as recommended by the current design code. The differential settlement between the abutments was small, 0.02 m (0.79″), and the residual rotation of the bridge was also small, about 0.001°. The residual horizontal movement of the bridge was small. However, the reduction in the stiffness of the saturated foundation soil led to the increased reliance of the backfill on the integral bridge abutments. This resulted in significantly higher bending moments in the bridge abutments and changes to the bending moment distribution along the abutment walls.